Holmes G M, Stephens R L, Bresnahan J C, Beattie M S
Department of Neuroscience, The Ohio State University, 4068 Graves Hall, 333 West Tenth Avenue, Columbus, OH 43210-1239, USA.
Physiol Behav. 2001 May;73(1-2):59-64. doi: 10.1016/s0031-9384(01)00440-1.
Intrathecal thyrotropin-releasing hormone (TRH) potently inhibits penile erection at all doses (100, 500, 1000 or 5000 pmol) tested so far. Since the serotonin receptor antagonist methiothepin (MT) inhibits TRH responses in other systems, this study tested the hypothesis that MT-sensitive receptors mediate the effect of TRH on penile erection in rats. When compared to controls, the highest doses of IT TRH (0, 10 or 500 pmol) or MT (5 or 50 nmol) significantly altered penile reflex latency. When coadministered (50 nmol MT/500 pmol TRH), the effect of TRH was reversed, suggesting that the high dose of MT antagonized the inhibitory actions of TRH. The low dose of MT (5 nmol) did not block the 500 pmol TRH inhibition of reflex latency. These data further suggest that MT sensitive receptors are important in (1) mediating normal penile reflexes and (2) mediating the inhibitory response to TRH.
鞘内注射促甲状腺激素释放激素（TRH）在目前所测试的所有剂量（100、500、1000或5000皮摩尔）下均能有效抑制阴茎勃起。由于5-羟色胺受体拮抗剂甲硫噻平（MT）在其他系统中能抑制TRH反应，本研究检验了MT敏感受体介导TRH对大鼠阴茎勃起作用的假说。与对照组相比，鞘内注射TRH（0、10或500皮摩尔）或MT（5或50纳摩尔）的最高剂量显著改变了阴茎反射潜伏期。当联合给药（50纳摩尔MT/500皮摩尔TRH）时，TRH的作用被逆转，这表明高剂量的MT拮抗了TRH的抑制作用。低剂量的MT（5纳摩尔）并未阻断500皮摩尔TRH对反射潜伏期的抑制作用。这些数据进一步表明，MT敏感受体在（1）介导正常阴茎反射和（2）介导对TRH的抑制反应中起重要作用。
